Phosphorescent Trinuclear Pt–Ir–Pt Complexes: Insights into the Photophysical and Electrochemical Properties and Interaction with Guanine Nucleobase

Abstract

Abstract In this study we have analysed the comparative photophysical and electrochemical properties of two isomeric heterotrinuclear Pt II –Ir III –Pt II complexes 3 and 6 and the four corresponding intermediate isomeric homonuclear cyclometalated iridium(III) complexes 1 , 2 , 4 and 5 . The isomerisation originates from positional differences in the formyl, di‐2‐picolylamine and Pt–di‐2‐picolylamine moieties appended to cyclometalated or ancillary ligands. The interaction of 5′‐GMP with the trinuclear complexes 3 and 6 shows that platinum centres appended to the cyclometalated ligand in 3 facilitate the binding of two 5′‐GMP units per Pt II centre in preference to a single 5′‐GMP unit per Pt II centre as observed in 6 . The 1:2 and 1:1 Pt II –5′‐GMP binding patterns probably arise from the convenient arrangements of the Pt–di‐2‐picolylamine units in different planes in complex 3 , which is absent in complex 6 .